Triggering an event activity

[briannoyes]

I have a workflow with an event activity named WaitForResubmitInput, how can I trigger it and can I pass parameters to it that can be used by a decision activity that follows the event activity?

[sfmskywalker]

Yes. The Event activity waits on its configured event name, so publish that name through IEventPublisher. For an event that is waiting inside an existing workflow instance, include that instance ID so the event is scoped to the correct workflow:

await eventPublisher.PublishAsync(
    "WaitForResubmitInput",
    workflowInstanceId: workflowInstanceId,
    payload: new { approved = true, comment = "resubmitted" },
    cancellationToken: cancellationToken);

The Event activity writes that payload to its result when it resumes. In the designer, bind the Event activity result to a workflow variable, then use that variable in the following decision activity (for example, inspect approved).

If you omit workflowInstanceId, the event is delivered by name (and optionally correlation ID), which is appropriate for an Event configured as a workflow trigger but is usually too broad for resuming one already-running instance. For an external HTTP caller, expose an authenticated application endpoint that calls IEventPublisher rather than relying on the token-based public event URL; the latter only carries its generated token and does not accept an arbitrary payload.

Relevant source: Elsa.Workflows.Runtime/Activities/Event.cs, Services/EventPublisher.cs, and the Event component tests. Those tests also verify that a payload reaches the consuming Event activity.